Conventional terephthalic acid (TPA) manufacturing processes require relatively high p-xylene purity (99.7+%) in order to improve the quality of the product and reduce the costs of manufacturing. This is due to the fact that such prior art processes use hydrogenation as the main method for purifying the crude terephthalic acid produced in the oxidation section of said processes. Although the hydrogenation method is very selective to eliminate the major impurity, 4-carboxybenzaldehyde (4-CBA) by converting it to p-toluic acid, the method only operates in the presence of a very small amount of 4-CBA (preferably less than 3,000 ppm). Also, the conventional TPA manufacturing processes are not capable of separating TPA from its isomers, such as isophthalic acid (IPA) and phthalic acid (PA).